370 LAKE SUPERIOR. 



smaller and subcircular. The lateral line curves slightly on the 

 abdomen as far as the height of the anterior margin of the dorsal, 

 whence it continues almost directly towards the tail, approaching 

 nearer, however, to the lower line of the body. 



Small circular shields with depressed surface, surmounted with 

 very small conical and acute points, cover the surface of the head, 

 the snout and the back, as far as the dorsal fin. A row of five or 

 six of the largest border the lower jaw ; those of middle size cover 

 the extremity of the snout and the space situated before the eyes. 

 On the back they are excessively small. 



The head and the back are of a bluish black, the sides and the 

 abdomen of a gold-colored yellow, everywhere with a metallic reflec- 

 tion. The fins are of uniform color and participate of the tint of 

 the regions to which they belong. 



From Montreal lliver on the eastern shore of Lake Superior. 



LEUCISCUS GRACILIS, Agass. 



There is still another Leuciscus which, at first sight, one might 

 be disposed to confound with L. cornutus or with the frontalis 

 above described. And it must be confessed that it has much anal- 

 ogy with those two species, between which it must be placed in a 

 natural series. 



In a family so numerous in species as that of the Cyprmidse, it is 

 only by minute study that we can succeed in making out the history 

 of each of them. Here, as in Europe, the species, though belonging 

 often to different genera, gradually pass from one genus to another, 

 in their general appearance ; the type of the family, that of the 

 genus itself, seems to predominate in all ; and by reason of the 

 multiplicity, and also the diversity of forms under which these 

 characters manifest themselves, the species appear to be mere varie- 

 ties. These difficulties occur also, in all genera which have numer- 

 ous species in other families of this and other classes, but, far from 

 impressing naturalists merely with the monotony to be overcome, 

 thev should render them attentive to the most minute details which 



/ 



characterize, in a permanent manner, natural groups in the animal 

 kingdom. In the case of this species and the two others mentioned 



